The Dynamic Earth

Question 1

Who was Alfred Wegener?

Answer 1

• continents not fixed but instead ‘floating’ on denser material in the mantle below
• continents constantly breaking apart and rejoining in new combinations

Question 2

What evidence is there for continental drift?

Answer 2

• the fit of the continents
• fossil distribution
• geological evidence (mountain ranges, ancients glaciers and coal deposits)
• living species

Question 3

What makes up the lithosphere?

Answer 3

Crust and the upper part of mantle

Question 4

What cause the tectonic plates to move?

Answer 4

Convection currents in the mantle cause the plates to move (hot, less dense magma rises while cooler, heavier magma sinks)

Question 5

What are the three types of plate boundaries?

Answer 5

Divergent, transform, convergent

Question 6

Divergent

Answer 6

• spreading
• magma from mantle spews onto earths surface and forms ridges
• results in mid-oceanic ridges

Question 7

Convergent

Answer 7

• collision
• one oceanic and one continental = subduction
• two continental =formation of mountains

Question 8

Transform boundaries

Answer 8

• sliding

- plates slide past eachother usually causing earthquakes

Question 9

How do earthquakes occur?

Answer 9

When tectonic plates are jammed together for a long period of time and suddenly slip releasing a massive amount of energy.

Question 10

Focus of earthquake

Answer 10

Where the earthquake occurs below the surface

Question 11

Epicentre of earthquakes

Answer 11

Where earthquakes occur above surface (above focus)

Question 12

What are the vibrations caused by earthquakes called?

Answer 12

Seismic waves

Question 13

Measuring/detecting/locating earthquakes

Answer 13

• seismogram uses p and L waves to indicated the intensity of earthquake
• location is found by comparing time between p and s waves

Question 14

P- waves

Answer 14

• primary
• compression waves
• first to hit seismometer because they are the fastest
• body wave

Question 15

S-waves

Answer 15

• secondary
• transverse waves
• come after p-waves
• body wave

Question 16

L-waves

Answer 16

• surface waves
• slow
• cause damage because they distribute their energy across earths surface rather than earths interior

Question 17

Shield cones

Answer 17

• low domes
• no explosive eruptions because lava is runny therefore gases escape
• made of layers of basalt that formed from very fluid, fast cooling lava

Question 18

Cinder cones

Answer 18

• pointed shape
• formed only after a few eruptions
• made of pyroclastic material (ejected materials e.g cinder, ash and volcanic rocks)

Question 19

Composite cones

Answer 19

• steep sides

- made of alternating layer of lava and pyroclastic material

Question 20

Where can volcanoes be found?

Answer 20

• ring of fire (pacific plate)
• hot spots above mantle plume
• plate boundaries

Question 21

Earths structure

Answer 21

1) inner core
2) outer core
3) mantle
4) crust

Question 22

Define magma

Answer 22

Magma is molten rock underground

Question 22

Define lava

Answer 22

Magma that comes out in the volcano

Question 23

Define vent

Answer 23

An opening exposed on the earths surface where volcanic material is emitted

Question 24

How was earth formed?

Answer 24

• dust/grains began to clump together collision b/w larger objects produced an asteroid size body
• growing body heats up due to form the energy of compression and collision
• dense molten metal particles sink and lighter float causing layers of earth

Question 24

What was pangea

Answer 24

All continents together

Question 24

Laurasia

Answer 24

Northern hemisphere continents together

Question 25

Gondwana

Answer 25

Southern hemisphere continents together

Question 26

What is the evidence for plate tectonics?

Answer 26

• chains of volcanoes (mark plate boundaries)
• increasing height of mountain ranges
• movement of continents (using gps)
• sea floor spreading

Question 27

What can we learn from earthquake data?

Answer 27

P waves can travel through core of earth and get refracted but s waves cannot